Because, as it constitutes an effective monopoly on search (monopoly doesn't mean "absolutely sole mean". There were other OSes besides Windows in the 90s too, and other telcos when Bell split (e.g. MCI)), it's ranking has enormous influence over news, information gathering, business, politics, and so on.

Too much to be left to some private interests to play with at their own opaque will (and sell to the highest bidder).